Field of the Invention
The invention generally relates to measurement reporting in a wireless communications system, and more particularly, to apparatuses and methods for measurement reporting in a wireless communications system associated with different Radio Access Technologies (RATs).
Description of the Related Art
In a typical mobile communications environment, a user equipment (UE) may communicate voice and/or data signals with one or more service networks via cellular stations of the service networks. The wireless communications between the UE and the service networks may be in compliance with various radio access technologies (RATs), such as the Global System for Mobile communications (GSM) technology, General Packet Radio Service (GPRS) technology, Enhanced Data rates for Global Evolution (EDGE) technology, Wideband Code Division Multiple Access (WCDMA) technology, Code Division Multiple Access 2000 (CDMA 2000) technology, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) technology, Worldwide Interoperability for Microwave Access (WiMAX) technology, Long Term Evolution (LTE) technology, Universal Mobile Telecommunications System (UMTS) technology and others.
To enable certain functionalities for UEs, such as handover (HO) between network nodes, it may be necessary for the UE to perform measurements, for example, of cells (i.e. the cellular stations) on a certain frequency or systems. To perform these measurements, the UE may require a measurement configuration for the purpose of performing measurements in the same or other frequencies and other radio access technologies (RATs). The service network (i.e. E-UTRAN in LTE) can configure the UE to report measurement information to support the control of UE mobility. The measurement configurations can be signaled via the RRCConnectionReconfiguration message. Measurement configurations may include a number of measurement types, such as inter-frequency measurements, intra-frequency measurements, and inter-RAT measurements which may assist the service network for handover (HO) purposes. For both the UMTS and LTE technologies, these measurement types are configured by the service network, and the UE may report measurement information on a certain frequency or RAT, if the UE is configured with such events. The measurement configurations may at least comprise measurement objects which are the objects on which the UE shall perform the measurements. The measurement procedures distinguish the following types of cells: the Serving cell, Listed cells and Detected cells, wherein the Serving cell is the cell that the UE has camped on, the Listed cells are cells listed within the measurement object(s) and the Detected cells are cells that are not listed within the measurement object(s) but are detected by the UE on the carrier frequency(ies) indicated by the measurement object(s).
Particularly, in the design of current service networks, a home cell, such as a Closed Subscriber Group (CSG) cell, a hybrid cell, a femtocell, a picocell or other home cell can use a small coverage cellular base station, called Home Node-B (HNB), or Home e-Node-B (HeNB); which is typically designed for use in residential or small business environments. The home cell connects to a service provider network via a wired or wireless backhaul connection. For example, home cells (e.g. CSG cells or hybrid cells) or the HNBs or HeNBs are used for deployment in school campuses or are used for deployment in users' homes. When being configured to operate in an open access mode, the HNB or HeNB may provide service access to subscribers of any service network (subject to the roaming agreement reached therebetween). Specially, the HNB or HeNB may be associated with a CSG and may only provide service access to the subscribers belonging to the associated CSG when operating in a closed access mode.
Conventionally, for inter-RAT Universal Terrestrial Radio Access (UTRA) technology measurements, the UE measures and reports on listed cells which are cells listed within the measurement object(s) to be measured. Note that the current working assumption in the 3GPP specification is that the CSG cells of a home deployment types are not indicated within the neighboring cell list.